Turbocharger systems are frequently used to improve the efficiency of internal combustion engines. Two-stage turbocharger systems can be used to further improve the engine efficiency over a single-stage turbocharger system including a single turbine and a single compressor. While use of two-stage turbocharger systems may be desirable in automotive vehicles, for example, to achieve fuel economy targets or other environmental goals, the combination of the added financial cost in conjunction with the size, packaging, assembly, or installation constraints may be prohibitive. Additionally, introducing turbines into the exhaust gas flow can reduce the temperature of the exhaust gas and may reduce the effectiveness of downstream emissions control devices, such as a catalytic converter. Accordingly, it is desirable to provide a turbine housing having lower thermal inertia while also achieving other performance objectives and maintaining structural integrity.